Loss of visual acuity is a growing concern worldwide. The World Health Organization currently estimates to 2.5% the incidence of low vision in industrialized countries and this figure is expected to continue to increase with ageing population. Low vision may be generally referred to as a condition where ordinary eye glasses, lens implants or contact lenses are not sufficient for providing sharp sight. The largest growing segment of the low-vision population in developed countries is expected to be people aged 65 years old and older. This is mainly due to age-related eye diseases such as macular degeneration, glaucoma and diabetic retinopathy, cataract, detached retina, and retinitis pigmentosa. Some people are also born with low vision.
Low-vision individuals often find it difficult, if not impossible, to read small writing or to discern small objects without high levels of magnification. This limits their ability to lead an independent life because reading glasses and magnifying glass typically cannot provide sufficient magnification for them. In order to assist low-vision individuals in performing daily tasks, various magnification devices and systems are known in the art.
Among such devices and systems, desktop video magnifiers generally include a video monitor mounted on a frame structure having a gooseneck shape. A camera provided with optical zooming capabilities is mounted on the frame structure and disposed so that the field of view of the camera intersects a working area on which a user can dispose an object of interest to be magnified. For example, the object may be a document including text content that the user wishes to read. The camera feeds a video processor with a video stream of a portion of the working area, and the video processor in turn feeds this video stream with an increased sharpness and enhanced contrast to the video monitor.
In conventional video magnifiers, the camera typically has a relatively narrow field of view and, therefore, can only acquire a video stream of a limited portion of the working area. In such cases, the user must displace the document with respect to the field of view of the camera in order to access different portions of the document. To assist the user in this task, the working area on which the document is placed is typically an XY translation table assembled on rails. Such a configuration allows the user to freely move the XY table and the document thereon to bring different portions of the document within the field of view of the camera. In other words, in conventional video magnifiers, panning across the image or video stream of the document may be achieved by moving the XY table and the document thereon with respect to the field of view of the camera. Moving the XY table is often considered a difficult task by users, because they must translate the table in a direction which is often considered counterintuitive. For example, to view the region at the left of the currently displayed image, the XY table must be moved to the right. Hence, panning in conventional video magnifiers is not considered optimal for certain applications, thereby negatively impacting the efficiency, functionality and ease-of-use of these devices.
In view of the above considerations, there is therefore a need in the art for an improved panning system and method that can be used more easily and conveniently by low-vision individuals or other users, while also alleviating at least some of the drawbacks of the prior art.